General engineering information; project-specific suitability requires review. General information does not establish a Xinwei product rating or suitability for a specific application.
A polymer family is a screening step
Begin with the exact exposure and mechanical task. A family label such as NBR, EPDM or silicone does not define fillers, cure system, additives, hardness, color or finished-part behavior. The objective of screening is to identify candidates and questions, followed by review of an identified compound and the actual component.
Write the exposure record before comparing names
List each medium and concentration, including cleaning chemicals, assembly lubricant and occasional contamination. Record temperature with time: continuous operation, short peaks, shutdown, cold start and cleaning. Add pressure, motion, compression and any required regulatory evidence.
- A seal that sees coolant internally and oil splash externally has two exposures.
- A wash part's detergent cycle is not described by water temperature alone.
- A vent line may see vapor, condensate and oil mist rather than a single liquid.
Use general references narrowly
Trelleborg's automotive material descriptions place NBR in oil-resistance screening, describe EPDM in water/coolant and weathering contexts, and explain that FKM and HNBR properties vary with formulation details. Its EPDM coating reference also warns about petroleum-fluid exposure. These are reasons to ask compound-specific questions, not proof that one family's member fits every task.
- Oil service: identify the actual oil and additives before evaluating an NBR or other candidate.
- Water/coolant service: identify the complete mixture before evaluating an EPDM or other candidate.
- Heat and chemical service: do not select FKM solely from a temperature headline.
- Silicone projects: assess mechanical duty, fluid exposure and any food-contact evidence separately.
Do not turn hardness into a material identity
If a hardness is required, state the numerical target, scale, test method and acceptance basis. Two compounds with the same stated hardness may have different compatibility and mechanical behavior. A color or a touch comparison is not enough to identify the material supplied.
Close the gap between reference and part
Request the proposed compound identity and the documents relevant to your specification. Decide which material checks and assembled tests are needed. A compatibility chart may help eliminate an obviously unsuitable candidate, but it cannot establish leakage, life or cleanliness in an untested finished geometry.
Keep a short decision record
For each candidate, write the evidence that supports further review, unresolved exposures and the test or document that would resolve them. If a required compound is not available or its evidence is incomplete, record that explicitly rather than substituting a family name.
- Candidate and specific formulation proposed.
- Media/time/temperature conditions used for review.
- Mechanical and assembly requirements still to validate.
- Document identity, report scope and acceptance owner.
What this guide does not establish
The sources are third-party technical context. Their compounds, certifications and numeric service ranges are not Xinwei specifications. No candidate family in this guide is a confirmed available Xinwei formula until the project proposal identifies it.
Related project families
General references and scope
These references explain general engineering or regulatory context. They are not Xinwei finished-product specifications, test results or compliance evidence.
- Automotive Materials — English technical body on an official localized URL. General NBR, EPDM, FKM and HNBR selection context; formulation and exposure conditions matter. No supplier-specific numbers are transferred.
- Ethylene-propylene Terpolymers (EPDM) — Coating-specific source, used narrowly for the screening caution about petroleum fluids versus water/weather exposure; not a seal or hose grade approval.